The correct answer is: D. All of the above
Resistors are used in linear ICs to create voltage dividers, which are used to amplify or attenuate signals. The ratio of the two resistors in a voltage divider determines the gain of the amplifier. In order to achieve a desired gain, it is necessary to use resistors with precise values. However, it is not possible to manufacture resistors with perfectly precise values using IC processes. Therefore, resistor ratio design is used to create voltage dividers with the desired gain, even though the individual resistors may not have perfectly precise values.
Here is a more detailed explanation of each option:
- A. Ratios increase input resistance
The input resistance of an amplifier is the amount of resistance that it presents to the signal source. A higher input resistance means that the amplifier draws less current from the signal source, which can improve the signal-to-noise ratio. The input resistance of an amplifier is determined by the ratio of the two
resistors in the voltage divider that forms the input stage of the amplifier.- B. Ratios increase amplifier gain
The gain of an amplifier is the amount by which it amplifies the input signal. A higher gain means that the output signal is larger than the input signal. The gain of an amplifier is determined by the ratio of the two resistors in the voltage divider that forms the input stage of the amplifier.
- C. Precise resistor values are not possible with IC processes
It is not possible to manufacture resistors with perfectly precise values using IC processes. This is because the manufacturing process introduces variations in the resistance of the resistors. These variations can be caused by factors such as the temperature of the wafer during manufacturing, the amount of dopant that is added to the wafer, and the thickness of the oxide layer on the wafer.
Therefore, resistor ratio design is used to create voltage dividers with the desired gain, even though the individual resistors may not have perfectly precise values. By carefully choosing the ratio of the two resistors, it is possible to create a voltage divider with the desired gain, even though the individual resistors may have variations in their resistance.